120 



Furthermore the rods from the oral disk and the tentacles are of 

 great systematic value and, together with the numerous madreporic 

 canals, afford the main character for separating this genus from Euapta. 



Key to the species of Opheodesoma. 



1. Dorsal side of body distinctly striped (Pl. II Fig. 2-3), ventral side uni- 

 formly grey lineata 



Dorsal side of body never striped, but either mottled or of uniform colour 2 



2. Digits united by a web 3 



Digits not united by a web 5 



3. Rods present in both the oral disk and the tentacles. Cartilaginous 



ring very faint or nearly wanting clarki 



Rods present in oral disk but wanting in tentacles 4 



4. Cartilaginous ring voluminous and quite enclosing the weak calcareous 



ring spectabilis 



Cartilaginous ring not so voluminous that it encloses the stout cal- 

 careous ring glabra 



5. Rods present in both the oral disk and the tentacles. Calcareous ring 



green serpentina 



Rods wanting in both the oral disk and the tentacles. Calcareous ring 



green variabilis 



Rods wanting in tentacles but present in oral disk. Calcareous ring pure 

 white 6 



6. Anterior processes of the radiais of nearly the same length as the 



calcareous ring itself (Fig. 4. 7) grisea 



Anterior processes of the radiais not more than one third of the length 



of the calcareous ring itself (Fig. 4. 1) mauritiae 



Opheodesoma spectabilis Fisher. 



Opheodesoma spectabilis. Fisher. 1907. The Hawaiian Holothurians. pag. 



723. PI. 66, PI. 80 Fig. 1 a-d and PI. 81 Fig. 2. 

 Opheodesoma spectabilis. Clark. 1908. The Apodous Holothurians. 

 pag. 75. 



Taba Bay, Mindanao. 12. III. 1914. The shore. 1 specimen. 



The single specimen at hand measures 113 cm in length. It 

 is uniformly bluish-grey, and the ventral side of body is somewhat 

 lighter than the dorsal. Protuberances are totally wanting. It has 

 15 tentacles with the digits united by a web. On the oral side 

 of the tentacles there are faint eye-spots. The cartilaginous ring is 

 very voluminous and encloses the weak calcareous ring. All the 

 pieces of the calcareous ring have anteriorly a low process, and 

 the processes are united by a distinct membrane (Fig. 4. 6). The 



